Move To New Server From Backup File

I recently discontinued the use of my former web host and have chosen another one, yet I currently have no access to the old cPanel from my former host. I have a final backup file (tar.gz) and access to the new cPanel, but I have yet to find a way completely transfer my blog to the new host without usage of the old host/cPanel. Any ideas?

Is there at least still a way to create a WXR file?